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Paleomagnetic and 40 Ar/ 39 Ar evidence for remagnetization of Mesozoic oceanic rocks on the Vizcaino Peninsula, Baja California Sur, Mexico
Author(s) -
Hagstrum Jonathan T.,
Martínez Margarita López,
York Derek
Publication year - 1993
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/93gl02010
Subject(s) - paleomagnetism , geology , pillow lava , apparent polar wander , cretaceous , paleontology , mesozoic , fold (higher order function) , red beds , volcanic rock , structural basin , mechanical engineering , volcano , engineering
Previously published paleomagnetic data for Upper Jurassic pillow lavas of the Vizcaino Peninsula indicate that they were deposited near a paleolatitude of 14°N or S. Whether or not this result implies northward transport with respect to the continental interior has been controversial due to the lack of reliable Jurassic reference poles for the North American plate. Available paleomagnetic data for nearby Upper Triassic pillow basalts and overlying pelagic sediments at Punta San Hipólito, however, fail a fold test indicating that these rocks were remagnetized post‐folding. Indistinguishable in‐situ paleomagnetic directions and perturbed 40 Ar/ 39 Ar age spectra for the Triassic and Jurassic pillow lavas are consistent with resetting of their magnetic and isotopic systems in the middle Cretaceous, probably during burial by the overlap Valle Formation (>10 km thick). Resetting apparently occurred post‐deformation so the paleolatitude of remagnetization is unknown. High‐coercivity directions from a few samples of the Triassic rocks might represent an older magnetization acquired during deposition at paleolatitudes near 6°N or S.